Current Research
Student Performance and Perceptions of A&P Across F2F, Hybrid, and Online Teaching Lab Styles
Health science represents the fastest-growing industry in the US, a trend not predicted to slow for the next decade. The high demand for health professionals has led to increased demand for Anatomy & Physiology (A&P) courses and a transition to hybrid style labs to meet the necessary increased enrollment without increasing the need for lab space and compromising educational quality. The transition to hybrid style labs has only accelerated and become more important with the COVID-19 pandemic. It has been relatively unclear, however, how the hybrid style has impacted student learning, satisfaction, and performance. Furthermore, there is a general lack of research investigating the advantages and disadvantages across hybrid, online, and face-to-face styles. This lack of research is particularly obvious within biological sciences, including A&P. Attendance, practical grades, and overall grades were compared between face-to-face, hybrid, and online A&P lab styles. A survey was administered to compare student perceptions and experiences between hybrid and online lab styles. The hybrid style had many of the same advantages as online and face-to-face styles, yet very few disadvantages. Hybrid lab students reported better experiences, greater satisfaction, attended more labs, and outperformed online lab students. Face-to-face lab students, however, outperformed hybrid lab students. These findings can ultimately inform how to best implement, organize, and improve hybrid style labs to maximize student learning, achievement, and enjoyment.
Effects of Ectoparasitism on Growth in Eastern Fence Lizards
Parasitism is nearly ubiquitous in animals and is frequently associated with fitness costs in host organisms, including reduced growth, foraging, and reproduction. In many species, males tend to be more heavily parasitized than females and thus may bear greater costs of parasitism. Sceloporus undulatus is a female-larger, sexually-size dimorphic lizard species that is heavily parasitized by chigger mites (Eutrombicula alfreddugesi). In particular, the intensity of mite parasitism is higher in male than in female juveniles during the period of time when sex differences in growth rate lead to the development of sexual size dimorphism (SSD). Sex-biased differences in fitness costs of parasitism have been documented in other species. We tested whether a sex-biased growth cost of parasitism contributes to the development of SSD in S. undulatus. We measured growth and mite loads in two cohorts of unmanipulated, field-active yearlings by conducting descriptive mark-recapture studies during the activity seasons of 2016 and 2019. Yearling males had consistently higher mid-summer mite loads and consistently lower growth rates than females. However, we found that growth rate and body condition were independent of mite load in both sexes. Furthermore, growth rates and mite loads were higher in 2019 than in 2016. Our findings suggest that juveniles of S. undulatus are highly tolerant of chigger mites and that any costs imposed by mites must be at the expense of functions other than growth. We conclude that sex-biased mite ectoparasitism does not contribute to sex differences in growth rate and the development of SSD.
Seasonal Variation in Ectoparasitism in Eastern Fence Lizards
The natural histories of parasites and their hosts are intertwined, and intensity of parasitism depends on parasite abundance and host behavior, as well as potential effects of sex/age. To characterize potential effects of parasite abundance and host sex/age on chigger mite (Eutrombicula alfreddugesi) ectoparasitism on Eastern Fence Lizards (Sceloporus undulatus), we measured (1) the abundance of mites in the environment as well as mite load and prevalence on lizards throughout the activity season; (2) sex- and age-specific patterns of ectoparasitism; and (3) week-to-week consistency of mite loads on lizards. Environmental mite abundance varied seasonally in close association with mean monthly temperatures and was the main driver of pronounced seasonal variation in mite loads on lizards. Mite loads were almost always higher on yearlings than adults and, somewhat unexpectedly, were never higher on adult males than any of the other age-sex classes. As adults, females had higher mite loads than males in June–July, but as yearlings, males had higher mite loads than females in July–September. Despite considerable week-to-week variation, rank-ordering of lizard mite loads was highly consistent. These findings indicate that (1) consistent age-specific sex biases are superimposed on strong seasonal variation in mite loads and (2) detrimental effects of mites are expected to be consistently stronger in some individuals than others.
Effects of DHT on Growth and Color Development in Eastern Fence Lizards
Sexual differences in adult body size (sexual size dimorphism; SSD) and color (sexual dichromatism) are widespread, and both male- and female-biased dimorphisms are observed even among closely related species. A growing body of evidence indicates testosterone (T) can regulate growth, thus the development of SSD, and sexual dichromatism. However, the mechanism(s) underlying these effects are conjectural, including possible conversions of T to estradiol (E2) or 5 a-dihydrotestosterone (DHT). In the present study, we hypothesized that effects of T are physiological responses mediated by androgen receptors, and we tested two specific predictions: 1) that DHT would mimic effects of T by inhibiting growth and enhancing coloration, and 2) that removal of endogenous T via surgical castration would stimulate growth. We also hypothesized that females share downstream regulatory networks with males and predicted that females and males would respond similarly to DHT. We conducted experiments on eastern fence lizards (Sceloporus undulatus), a female-larger species with striking sexual dichromatism. We implanted Silastic tubules containing 150 mg DHT into intact females and intact and castrated males. We measured linear growth rates and quantified color for ventral and dorsal surfaces. We found that DHT decreased growth rate and enhanced male-typical coloration in both males and females. We also found that, given adequate time, castration alone is sufficient to stimulate growth rate in males. The results presented here suggest that (1) effects of T on growth and coloration are mediated by androgen receptors without requiring aromatization of T into E2 and (2) females possess the androgen-receptor mediated regulatory networks required for initiating male-typical inhibition of growth and enhanced coloration in response to androgens.
